Extra-axial cavernous malformations of the foramen magnum: illustrative cases.

BACKGROUND: Extra-axial cavernous malformations involving the foramen magnum are rare, and preoperative diagnosis becomes difficult when they mimic meningiomas. OBSERVATIONS: The authors present 2 cases of extra-axial cavernous malformations involving the foramen magnum. Surgical removal of the lesions was performed via far lateral craniotomy. The authors investigate the disease and elaborate the differential diagnosis. LESSONS: The authors recommend that extra-axial cavernous malformations should be considered in the differential diagnosis of lesions in the foramen magnum region. Intraoperative frozen sections are helpful to the diagnosis, and resection warranted a favorable long-term outcome.